Rolling of a rolled material

ABSTRACT

The invention relates to a rolling apparatus for rolling a rolled material, and to a method for operating the rolling apparatus. The rolling apparatus has two rolling stands, which each have two working rolls distanced from one another by a nip, through which the rolled material can be guided. In a first operating mode, a lubricant mixture, formed of a carrier gas and a lubricant, and coolant are applied to at least one working roll of a first rolling stand and/or to at least one rolled material surface of the rolled material. In a second operating mode, a skin pass agent is applied to at least one working roll of the first rolling stand, at least one working roll of the second rolling stand and/or at least one rolled material surface of the rolled material.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase application of PCT Application No. PCT/EP2018/069635, filed Jul. 19, 2018, entitled “ROLLING OF A ROLLED MATERIAL”, which claims the benefit of European Patent Application No. 17194457.2, filed Oct. 2, 2017, each of which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to a rolling apparatus for rolling a metal stock and to a method for operating the rolling apparatus.

2. Description of the Related Art

During rolling of a metal stock in a mill train of a rolling mill, the metal stock is generally deformed in one or more rolling passes. Particularly in the case of cold rolling of a metal stock there is often disposed at the end of a process route a rolling apparatus which has two roll stands and can be operated in two different operating modes.

In a first operating mode, the thickness of the metal stock is significantly reduced in the first roll stand of the rolling apparatus, e.g. by more than three percent compared to the thickness of the metal stock entering the first roll stand. In the second roll stand, on the other hand, the metal stock is primarily finished, i.e. a desired surface roughness of the metal stock is produced, wherein the thickness of the metal stock is only slightly reduced, e.g. by less than three percent compared to the thickness of the metal stock entering the second roll stand.

The first operating mode is typically used for producing relatively hard and thin steel sheet, e.g. for producing tinplate having a thickness of less than 0.5 mm which is used for canning food products. The metal stock is first rolled in the mill train to a thickness that is approximately in the region of a desired final thickness of the metal stock. As a correspondingly large number of rolling steps, or a correspondingly large per-pass reduction, is generally required for this purpose, the stock is relatively brittle and short after these rolling steps or passes, for which reason it is then heat-treated e.g. in an annealing furnace to restore the toughness of the material. The recrystallization of the material structure taking place here reduces the material hardness, which means that the metal stock can then be fed to the rolling apparatus.

In the second operating mode, on the other hand, the metal stock is mainly finished in both roll stands of the rolling apparatus without significant thickness reduction. The second operating mode is used, for example, for rolling a metal stock which is then coated with zinc and is generally somewhat thicker than the above mentioned tinplate.

As the metal stock is significantly reduced in thickness in the first roll stand in the first operating mode, the first operating mode requires adequate lubrication of the metal stock as it passes through the first roll stand, and cooling of the metal stock and the work rolls of the first roll stand after the stock has passed through the first roll stand. In this first operating mode, a lubricating emulsion having a relatively high lubricant content of 5 to 30% is therefore usually applied to the metal stock before it passes through the first roll stand. The lubricating emulsion used is generally an emulsion containing water and a rolling oil as lubricant. To cool the metal stock, a cooling emulsion generally containing water and a rolling oil having a relatively low rolling oil content is applied to the work rolls of the first roll stand and/or to the metal stock after passage through the first roll stand.

DE 10 2009 054 205 A1 discloses a method for cooling and cleaning in foundries, rolling mills or other strip processing plant, wherein castings, rolled stock or plant components are simultaneously cooled and cleaned and also possibly lubricated and sealed by a gas-liquid mixture.

WO 2012/079785 A1 discloses a method and a device for applying a lubricant during rolling of a metal stock. A mixture of lubricant and a carrier gas is produced in an atomization device and applied to at least one work roll and/or the rolled stock by means of an arrangement of spray nozzles.

SUMMARY OF THE INVENTION

The object of the invention is to specify a rolling apparatus and a method for the operation thereof that are improved particularly in respect of lubricant and coolant cost/consumption and the efficiency of the lubricating effect.

This object is achieved according to the invention by a rolling apparatus having the features as claimed in claim 1 and by a method having the features as claimed in claim 12.

Advantageous embodiments of the invention are set forth in the sub-claims.

An inventive rolling apparatus for rolling a metal stock comprises a first roll stand, a second roll stand spaced at a distance from the first roll stand, a lubricant mixture application device, a coolant application device and a finishing agent application device. Each roll stand comprises two work rolls separated by a roll gap through which the metal stock can be guided. The lubricant mixture application device is designed to apply a lubricant mixture consisting of a carrier gas and a lubricant to a side of a least one work roll of the first roll stand, said side facing away from the second roll stand, or/and to at least one surface of the metal stock on a side of the first roll stand facing away from the second roll stand, wherein the lubricant is a first rolling oil. Suitable rolling oils for lubricating a roll gap are well known and commercially available. The coolant application device is designed to apply coolant, e.g. cooling water or a cooling emulsion, to a side of a least one work roll of the first roll stand, said side facing the second roll stand, or/and to at least one surface of the metal stock on a side of the first roll stand facing the second roll stand. The finishing agent application device is designed to apply a finishing agent to a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, or/and to at least one surface of the metal stock on a side of the first roll stand facing away from the second roll stand and to a side of at least one work roll of the second roll stand, said side facing the first roll stand, or/and to at least one surface of the metal stock on a side of the second roll stand facing the first roll stand, wherein the finishing agent is an emulsion containing a second rolling oil and water. Suitable such finishing agents are well known and commercially available.

By means of the lubricant mixture application device, a lubricant mixture consisting of a carrier gas and a lubricant can be applied to the work rolls of the roll stand or/and to the metal stock in order to reduce friction between the metal stock and the work rolls of the first roll stand in the above mentioned first operating mode. Using a lubricant mixture consisting of a carrier gas and a lubricant has a number of advantages compared to using a lubricating emulsion. On the one hand it enables lubricant consumption to be reduced, as less lubricant is required to produce the lubricant mixture that is sprayed directly onto the work rolls or/and the metal stock than for producing a lubricating emulsion. On the other hand, it eliminates the complex/costly production and reconditioning of the lubricating emulsion normally used for lubrication.

The coolant application device enables the work rolls of the first roll stand and the metal stock to be cooled by means of a coolant. Using cooling water as a coolant has a number of advantages compared to using a cooling emulsion. A cooling emulsion can basically only be used above a particular minimum temperature, e.g. above approximately 40° C. to prevent mold formation and/or blockage of pipework. In contrast, cooling water can be used at lower temperatures, e.g. around 20° C., which produces a correspondingly better cooling effect compared to a lubricating emulsion. On the other hand, it eliminates the complex/costly production and reconditioning of the cooling emulsion normally used for cooling.

The finishing agent application device enables the metal stock to be finished using the finishing agent by the second roll stand in the first operating mode or by both roll stands in the second operating mode.

An embodiment of the invention provides that the carrier gas is air. Air is particularly suitable as a carrier gas, as it is inexpensive and environmentally friendly.

Another embodiment of the invention provides that the lubricant mixture application device has at least one atomization device to which the carrier gas and lubricant are fed and which is designed to produce the lubricant mixture from the carrier gas and the lubricant. This enables the lubricant mixture to be produced by the lubricant mixture application device in such a way that no lubricant mixture needs to be held in reserve.

Another embodiment of the invention provides that the lubricant mixture application device has a plurality of spray nozzles to which lubricant mixture can be supplied and which are designed to dispense the lubricant mixture. As a result, the lubricant mixture can be selectively applied and distributed by spray nozzles.

Another embodiment of the invention provides that the roll stands have at least one back-up roll for each work roll and the rolling apparatus has a cleaning fluid application device for applying a cleaning fluid to at least one back-up roll. Water or a cleaning emulsion, for example, is used as cleaning fluid. The cleaning fluid application device has, for example, a plurality of cleaning nozzles for dispensing the cleaning fluid. The cleaning fluid application device enables the back-up rolls to be cleaned of abraded material which collects on back-up roll surfaces. This cleaning is advantageous, as the roughening of the metal stock surface during the finishing process produces abrasion particles which, unless cleaned off, would increasingly contaminate the metal stock. As described above, the rolling apparatus is also preferably disposed at the end of the process route where a particularly high degree of cleanness of the metal stock is required.

Another embodiment of the invention provides for a coolant recirculation system to which the coolant application device is connected and which has, for each roll stand, a collecting device to collect coolant dripping from the roll stand, and a coolant conditioning device for cleaning the coolant collected by the collecting devices. This embodiment of the invention allows the coolant to be re-used, thereby advantageously reducing coolant consumption.

In the method according to the invention for operating a rolling apparatus according to the invention, in a first operating mode the lubricant mixture is applied to a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, or/and to at least one surface of the metal stock on a side of the first roll stand facing away from the second roll stand and the coolant is applied to a side of a least one work roll of the first roll stand, said side facing the second roll stand, or/and to at least one surface of the metal stock on a side of the first roll stand facing the second roll stand. In a second operating mode, the finishing agent is applied to a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, or/and to at least one surface of the metal stock on a side of the first roll stand facing away from the second roll stand and to a side of at least one work roll of the second roll stand, said side facing the first roll stand, or/and to at least one surface of the metal stock on a side of the second roll stand facing the first roll stand. The advantages of the method according to the invention follow from the above mentioned advantages of the rolling apparatus according to the invention.

An embodiment of the invention provides that, in the first operating mode, the finishing agent is applied to a side of at least one work roll of the second roll stand, said side facing the first roll stand, or/and to at least one surface of the metal stock on a side of the second roll stand facing the first roll stand. This embodiment enables the metal stock to be finished using a finishing agent in the first operating mode.

BRIEF DESCRIPTION OF THE DRAWINGS

The above described characteristics, features and advantages of the invention and the way in which they are achieved will become clearer and more readily comprehensible in conjunction with the following description of exemplary embodiments which will be explained in greater detail with reference to the accompanying drawings in which:

FIG. 1 schematically illustrates a rolling apparatus according to the prior art,

FIG. 2 schematically illustrates a rolling apparatus according to the invention.

Corresponding parts are provided with the same reference characters in the figures.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a prior art rolling apparatus 1 for rolling a metal stock 3. The rolling apparatus 1 has two roll stands 5, 7 arranged in tandem in a direction of rolling 9. Each roll stand 5, 7 has two work rolls 11 and a back-up roll 13 for each work roll 11. The two work rolls 11 of a roll stand 5, 7 are separated by a roll gap 15 through which metal stock 3 is passed. The back-up roll 13 of a work roll 11 is disposed on a side of the work roll 11 facing away from the roll gap 15.

The rolling apparatus 1 also comprises a lubricating emulsion application device 17, a cooling emulsion application device 19 and a finishing agent application device 21.

The rolling apparatus 1 is operated in two different operating modes. In a first operating mode, a first roll stand 5, which is disposed upstream of the second roll stand 7 in the direction of rolling 9 and through which the metal stock 3 therefore passes before the second roll stand 7, appreciably reduces the thickness of the metal stock 3, e.g. by more than three percent compared to the thickness of the metal stock 3 before it enters the first roll stand 5. In the second roll stand 7, on the other hand, the metal stock 3 is mainly finished, i.e. a desired surface roughness of the metal stock 3 is produced, wherein the thickness of the metal stock 3 is only slightly reduced, e.g. by less than three percent compared to the thickness of the metal stock 3 before it enters the second roll stand 7. In the second operating mode, the metal stock 3 is finished in both roll stands 5, 7 but without significant thickness reduction.

The lubricating emulsion application device 17 is used in the first operating mode to apply a lubricating emulsion to the metal stock 3 upstream of the first roll stand 5. The lubricating emulsion is applied to a top metal stock surface 25 and to a bottom metal stock surface 27 of the metal stock 3 by means of lubrication nozzles 23 of the lubricating emulsion application device 17. The lubricating emulsion contains water and a rolling oil and has a relatively high rolling oil content of e.g. 5 to 30%.

The cooling emulsion application device 19 is used in the first operating mode to apply a cooling emulsion to the work rolls 11 of the first roll stand 5 or/and to the metal stock 3. The cooling emulsion is applied by means of cooling nozzles 29 of the cooling emulsion application device 19 to the sides of the work rolls 11 of the first roll stand 5, said sides facing the second roll stand 7, or/and to the top metal stock surface 25 and the bottom metal stock surface 27 of the metal stock 3 on a side of the first roll stand 3 facing the second roll stand 7.

In both operating modes, the finishing agent application device 21 applies a finishing agent to the work rolls 11 of the second roll stand 7 or/and to the metal stock 3 in the region of the roll gap 15 of the second roll stand 7. Finishing nozzles 31 of the finishing agent application device 21 are used to apply the finishing agent to the sides of the work rolls 11 of the second roll stand 7 that face the first roll stand 5 or/and to the top metal stock surface 25 and the bottom metal stock surface 27 of the metal stock 3 on a side of the second roll stand 7 facing the first roll stand 5. The finishing agent is a finishing emulsion containing water and a rolling oil, said finishing emulsion having a lower rolling oil content and a different rolling oil than the lubricating emulsion.

In addition, in the second operating mode the finishing agent application device 21 also applies the finishing agent to the work rolls 11 of the first roll stand 7 or/and to the metal stock 3 in the region of the roll gap 15 of the first roll stand 7. Other finishing nozzles 31 of the finishing agent application device 21 are used to apply the finishing agent to the sides of the work rolls 11 of the first roll stand 5 that face away from the second roll stand 7 or/and to the top metal stock surface 25 and the bottom metal stock surface 27 of the metal stock 3 on a side of the first roll stand 5 facing away from the second roll stand 7.

The rolling apparatus 1 also has a cleaning fluid application device 33 for applying a cleaning fluid to back-up rolls 13 of the roll stands 5, 7 in order to clean the back-up rolls 13 of abraded material accumulating on the surfaces of the back-up rolls 13. The cleaning fluid is dispensed onto the back-up rolls 13 by means of cleaning nozzles 35 of the cleaning fluid application device 33. FIG. 2 only shows cleaning nozzles 35 for the back-up rolls 13 disposed above the work rolls 11. However, the cleaning fluid application device 33 can additionally have other cleaning nozzles 35 for the back-up rolls 13 disposed below the work rolls 11. Water or a cleaning emulsion, for example, is used as cleaning fluid.

FIG. 2 shows a rolling apparatus 1 according to the invention. This rolling apparatus 1 differs from the rolling apparatus 1 shown in FIG. 1 in that it has a lubricant mixture application device 37 instead of the lubricating emulsion application device 17. The rolling apparatus 1 also has a coolant application device 39 from which a coolant can be delivered which is either cooling water or a cooling emulsion.

The rolling apparatus 1 shown in FIG. 2 is also operated in two different operating modes. In a first operating mode, the thickness of the metal stock 3 is again appreciably reduced in the first roll stand 5, e.g. by more than three percent compared to the thickness of the metal stock 3 upstream of the first roll stand 5, and, in the second roll stand 7, the metal stock 3 is mainly finished, wherein the thickness of the metal stock 3 is only slightly reduced, e.g. by less than three percent compared to the thickness of the metal stock 3 upstream of the second roll stand 7. In the second operating mode, the metal stock 3 is finished in both roll stands 5, 7 of the rolling apparatus 1, again without significant thickness reduction.

The lubricant mixture application device 37 is used in the first operating mode to apply a lubricant mixture to the sides of the work rolls 11 of the first roll stand 5 facing away from the second roll stand 7 or/and to the top metal stock surface 25 and the bottom metal stock surface 27 of the metal stock 3 on a side of the first roll stand 5 facing away from the second roll stand 7. The lubricant mixture is a mixture of a carrier gas and a lubricant. Air, for example, is used as a carrier gas. A rolling oil, for example, is used as a lubricant. For each metal stock surface 25, 27, the lubricant mixture application device 37 has an atomization device 41 to which the carrier gas is supplied via a carrier gas pipe 43 and the lubricant via a lubricant pipe 45 and which is designed to produce the lubricant mixture from the carrier gas and the lubricant. The lubricant mixture application device 37 also has a plurality of spray nozzles 47 to which lubricant mixture produced by an atomization device 41 can be supplied in each case. The spray nozzles 47 fed with the lubricant mixture by an atomization device 41 are distributed over the width of the metal stock 3 and spray the metal stock 3 evenly across the width thereof with the lubricant mixture on the respective metal stock surface 25, 27.

The coolant application device 39 is used in the first operating mode, on the downstream side of the first roll stand 5, to apply coolant (cooling water or a cooling emulsion) to the work rolls 11 of the first roll stand 5 or/and to the metal stock 3. The coolant is applied by means of coolant nozzles 49 of the coolant application device 39 to the sides of the work rolls 11 of the first roll stand 5 facing the second roll stand 7 or/and to the top metal stock surface 25 and the bottom metal stock surface 27 of the metal stock 3 on a side of the first roll stand 3 facing the second roll stand 7.

The rolling apparatus 1 also has a finishing agent application device 21 and a cleaning fluid application device 33 which are designed and used in the same way as in the rolling apparatus 1 shown in FIG. 1 and will not therefore be described again here.

The rolling apparatus 1 also has a coolant recirculation system 51 to which the coolant application device 39 is connected. The coolant recirculation system 51 has, for each roll stand 5, 7, a collecting device 53 for collecting coolant dripping off the roll stand 5, 7, and a coolant conditioning device 55 for cleaning the coolant collected in the collecting devices 53. During cleaning of the coolant in the coolant conditioning device 55, a rolling oil of the lubricant mixture, for example, and/or other matter, e.g. material that has been abraded from the metal stock 3, the work rolls 11 and/or the back-up rolls 13, is removed from the coolant.

Although the invention has been illustrated and described in detail by the preferred exemplary embodiments, the invention is not limited by the examples disclosed and other variations will be apparent to persons skilled in the art without departing from the scope of protection sought for the invention.

LIST OF REFERENCE CHARACTERS

-   1 rolling apparatus -   3 metal stock -   5, 7 roll stand -   9 direction of rolling -   11 work roll -   13 back-up roll -   15 roll gap -   17 lubricating emulsion application device -   19 cooling emulsion application device -   21 finishing agent application device -   23 lubrication nozzle -   25, 27 metal stock surface -   29 cooling nozzle -   31 finishing nozzle -   33 cleaning fluid application device -   35 cleaning nozzle -   37 lubricant mixture application device -   39 cooling water application device -   41 atomization device -   43 carrier gas pipe -   45 lubricant pipe -   47 spray nozzle -   49 coolant nozzle -   51 coolant recirculation -   53 collecting device -   55 cooling water conditioning device 

1-11. (canceled)
 12. A rolling apparatus for rolling a metal stock, said rolling apparatus comprising: a first roll stand and a second roll stand spaced at a distance from the first roll stand, wherein each roll stand has two work rolls separated from one another by a roll gap through which the metal stock can be passed; a lubricant mixture application device for applying a lubricant mixture consisting of a carrier gas and a lubricant to at least one of: a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, and at least one metal stock surface of the metal stock on a side of the first roll stand, said side facing away from the second roll stand, wherein the lubricant is a first rolling oil; a coolant application device for applying a coolant to at least one of: a side of at least one work roll of the first roll stand, said side facing the second roll stand, and at least one metal stock surface of the metal stock on a side of the first roll stand, said side facing the second roll stand; and a finishing agent application device for applying a finishing agent to at least one of: a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, and at least one metal stock surface of the metal stock on a side of the first roll stand, said side facing away from the second roll stand, and the finishing agent application device for applying the finishing agent to at least one of: a side of at least one work roll of the second roll stand, said side facing the first roll stand, and at least one metal stock surface of the metal stock on a side of the second roll stand, said side facing the first roll stand, wherein the finishing agent is an emulsion which contains a second rolling oil and water.
 13. The rolling apparatus as recited in claim 12, wherein the carrier gas is air.
 14. The rolling apparatus as recited in claim 12, wherein the coolant is one of cooling water and a cooling emulsion.
 15. The rolling apparatus as recited in claim 12, wherein the lubricant mixture application device has at least one atomization device to which the carrier gas and the lubricant are supplied and which is designed to produce the lubricant mixture from the carrier gas and the lubricant.
 16. The rolling apparatus as recited in claim 12, wherein the lubricant mixture application device has a plurality of spray nozzles to which lubricant mixture can be supplied and which are designed to dispense the lubricant mixture.
 17. The rolling apparatus as recited in claim 12, wherein the roll stands have, for each work roll, at least one back-up roll and the rolling apparatus has a cleaning fluid application device for applying a cleaning fluid to at least one back-up roll.
 18. The rolling apparatus as recited in claim 17, wherein the cleaning fluid is one of water and a cleaning emulsion.
 19. The rolling apparatus as recited in claim 17, wherein the cleaning fluid application device has a plurality of cleaning nozzles for dispensing the cleaning fluid.
 20. The rolling apparatus as recited in claim 12, further comprising a coolant recirculation system connected to the coolant application device, the coolant recirculation system having, for each roll stand, a collecting device for collecting coolant dripping off the respective roll stand, the coolant recirculation system further having a coolant conditioning device for cleaning the coolant collected by the collecting devices.
 21. A method for operating a rolling apparatus according to claim 12, wherein one of: in a first operating mode, the lubricant mixture is applied to at least one of: a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, and at least one metal stock surface of the metal stock on a side of the first roll stand, said side facing away from the second roll stand, and the coolant is applied to at least one of: a side of at least one work roll of the first roll stand, said side facing the second roll stand, and at least one metal stock surface of the metal stock on a side of the first roll stand, said side facing the second roll stand; and in a second operating mode, the finishing agent is applied to at least one of: a side of at least one work roll of the first roll stand, said side facing away from the second roll stand, and at least one metal stock surface of the metal stock on a side of the first roll stand, said side facing away from the second roll stand, and to at least one of: a side of at least one work roll of the second roll stand, said side facing the first roll stand, and at least one metal stock surface of the metal stock on a side of the second roll stand, said side facing the first roll stand.
 22. The method as recited in claim 21, wherein, in the first operating mode, the finishing agent is applied to at least one of: a side of at least one work roll of the second roll stand, said side facing the first roll stand; and at least one metal stock surface of the metal stock on a side of the second roll stand, said side facing the first roll stand. 